CN113325678A - Developing device and image forming apparatus - Google Patents

Abstract

The invention provides a developing device and an image forming apparatus. The developing device includes a housing having: a housing section that houses a developer; a rotating part which rotates to convey the developer stored in the storing part along the length direction; and a developing roller that holds the developer conveyed by the rotating portion, wherein at least a part of the housing portion is formed of metal over a region overlapping with a developer holding region of the developing roller in the longitudinal direction.

Description

Developing device and image forming apparatus

Technical Field

The invention relates to a developing device and an image forming apparatus.

Background

Conventionally, as a developing device, a device described in the following patent document 1 is known.

Japanese patent No. 3982212 (paragraph 0052, fig. 10, etc.) describes a developing device having a structure in which a lower casing and an upper casing are joined and assembled, the lower casing and the upper casing being formed of a synthetic resin, and the lower casing and the upper casing being obtained by dividing the casing into 2 parts in the vertical direction.

Disclosure of Invention

The invention provides a developing device and an image forming apparatus, wherein the rigidity can be improved compared with the case that at least one part of a containing part of a shell is not made of metal in a region overlapping with a developer holding region of a developing roller in the length direction.

According to the 1 st aspect of the present invention, there is provided a developing device including a casing having: a housing section that houses a developer; a rotating part which rotates to convey the developer stored in the storing part along the length direction; and a developing roller holding the developer conveyed by the rotary portion,

at least a part of the housing portion is formed of metal over a region overlapping with a developer holding region of the developing roller in the longitudinal direction.

According to claim 2 of the present invention, the supporting portion of the housing, which is engaged with the accommodating portion and supports the shaft portion of the developing roller, is molded from a material having electrical insulation properties.

According to claim 3 of the present invention, the 2 nd support portion of the housing, which supports the shaft portion of the rotating portion, is molded from an electrically insulating material and is integrated with the support portion, which supports the shaft portion of the developing roller.

According to claim 4 of the present invention, the cross section of the portion of the housing portion formed of the metal in the direction orthogonal to the longitudinal direction is formed of the same shape.

According to the 5 th aspect of the present invention, a convex portion that comes into contact with the other joining surface is provided on the joining surface of the portion of the housing portion formed of metal and at least one of the support portion and the 2 nd support portion, and the portion of the housing portion formed of metal is coupled to the support portion or the 2 nd support portion by a screw in a state where the convex portion comes into contact with the other joining surface.

According to claim 6 of the present invention, the convex portion is provided on the surface of the support portion to be joined or the surface of the 2 nd support portion to be joined.

According to claim 7 of the present invention, the convex portion is provided at least at a portion surrounding the periphery of the screw.

According to the 8 th aspect of the present invention, the portion of the housing portion molded from metal, the support portion, and the 2 nd support portion are joined to each other with an elastic member interposed therebetween at least in part of the surfaces joined to each other,

the elastic member has a thickness exceeding a protruding amount of the convex portion before the coupling.

According to the 9 th aspect of the present invention, the elastic member is attached to the joining surface of the support portion and the joining surface of the 2 nd support portion.

According to the 10 th aspect of the present invention, the portion of the housing portion formed of the metal is configured by joining a plurality of divided portions divided by a surface along the longitudinal direction as a boundary.

According to the 11 th aspect of the present invention, there is provided an image forming apparatus including the developing device.

(Effect)

According to the invention of claim 1, the rigidity can be improved as compared with a case where at least a part of the housing portion of the casing is not made of metal over a region overlapping with the developer holding region of the developing roller in the longitudinal direction.

According to the invention of claim 2, even when the developing bias is supplied to the shaft portion of the developing roller, the electrical insulation of the supporting portion supporting the shaft portion of the developing roller can be ensured, and the electric current does not flow through the portion of the housing portion formed of metal.

According to the invention of claim 3, not only the shaft portion of the developing roller but also the support portion that supports the shaft portion of the rotating portion can be integrally molded with the shaft portion of the developing roller, and electrical insulation can be ensured.

According to the 4 th aspect of the present invention, the portion of the housing portion molded from metal can be efficiently obtained by metal extrusion molding or drawing molding.

According to the aspect 5 of the present invention, as compared with the case where the portion molded from metal of the housing portion and the support portion or the 2 nd support portion are joined by screws in a state where the surfaces having no convex portion are joined to each other, by interposing the convex portion, both the portion molded from metal of the housing portion and the support portion or the 2 nd support portion can be joined more easily by positioning.

According to the invention of claim 6, as compared with the case where the convex portion is provided on the side of the portion of the housing portion formed of metal, the portion provided with the convex portion can be easily secured, and the joining surfaces of the portion of the housing portion formed of metal can be formed into the same shape surface.

According to the invention of claim 7, the portion of the housing portion formed of metal and the support portion can be positioned and coupled more reliably than in the case where the projection portion is not provided at the portion surrounding the screw.

According to the 8 th aspect of the present invention, compared to the case where the housing portion is joined with the elastic member interposed therebetween, the gap is suppressed from being generated in the surface of the housing portion where the metal-molded portion is joined to the support portion and the 2 nd support portion with the elastic member interposed therebetween.

According to the 9 th aspect of the present invention, the elastic member can be easily attached as compared with the case where the elastic member is attached to the side of the portion of the housing portion formed of metal.

According to the 10 th aspect of the present invention, the metal molded portion can be more accurately produced than in the case where the metal molded portion of the housing portion is not divided into a plurality of portions.

According to the image forming apparatus of claim 11 of the present invention, it is possible to configure the image forming apparatus including the developing device in which the rigidity is improved as compared with a case where at least a part of the housing portion of the housing of the developing device is not formed of metal over a region overlapping with the developer holding region of the developing roller in the longitudinal direction.

Drawings

Fig. 1 is a schematic diagram illustrating an image forming apparatus according to embodiment 1.

Fig. 2 is a schematic sectional view showing a developing device of embodiment 1.

Fig. 3 is a plan view showing a part of the developing device of fig. 2 (a part with an upper surface portion removed).

Fig. 4 is a schematic exploded view showing a part of the structure of the developing device of fig. 3.

Fig. 5 is a schematic sectional view showing a structure of a housing portion in a housing of the developing device of fig. 2.

Fig. 6 is a schematic perspective view showing a part of the structure of the housing part of fig. 5.

Fig. 7 (a) is an explanatory view showing a cross-sectional shape of a lower overlapping portion which is a part of the housing portion of fig. 6, and (B) is a schematic view showing a structure of a joint surface of the lower overlapping portion.

Fig. 8 is a schematic view showing one support portion in the housing of the developing device of fig. 2.

Fig. 9 is a conceptual diagram illustrating a configuration related to the coupling of the overlapping portion of the lower portion of the housing and the support portion, (a) is a conceptual diagram illustrating a state before the coupling, and (B) is a conceptual diagram illustrating a state after the coupling.

Detailed Description

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

Embodiment 1.

Fig. 1 and 2 are drawings showing embodiment 1 of the present invention. Fig. 1 shows an image forming apparatus 1 according to embodiment 1, and fig. 2 shows a developing apparatus according to embodiment 1.

As shown in fig. 1, an image forming apparatus 2, a paper feeding apparatus 3, a fixing apparatus 4, and the like are provided inside a casing 10 of an image forming apparatus 1, wherein the image forming apparatus 2 forms a toner image formed of toner as a developer by an electrophotographic method or the like and transfers the toner image onto a recording paper 9 as an example of a recording material, the paper feeding apparatus 3 supplies a necessary recording paper 9 stored therein to a transfer position of the image forming apparatus 2, and the fixing apparatus 4 fixes the toner image transferred onto the recording paper 9.

As shown in fig. 1, the image forming apparatus 2 is configured by arranging devices such as a charging device 22, an exposure device 23, a developing device 5, a transfer device 25, a cleaning device 26, and a charge removing device 27 in this order around a photosensitive drum 21 that rotates in the direction indicated by the arrow a.

The photosensitive drum 21 is a drum-shaped photosensitive body having a photosensitive layer on its circumferential surface, is rotatably supported by a support frame or the like, not shown, and is rotationally driven in the direction indicated by the arrow a by receiving power from a driving device, not shown. The charging device 22 charges the peripheral surface (image forming region) of the photosensitive drum 21 to a desired polarity and a desired potential by a charging member to which a charging bias is supplied.

The exposure device 23 exposes light corresponding to image information (signals) input to the image forming apparatus 1 in various ways on the charged peripheral surface of the photosensitive drum 21, thereby forming an electrostatic latent image. The developing device 5 supplies toner as a developer to develop the electrostatic latent image on the photosensitive drum 21 into a toner image. The developing device 5 will be described in detail later.

The transfer device 25 electrostatically transfers the toner image on the photosensitive drum 21 to the recording paper 9 by a transfer member to which a transfer bias is supplied. The cleaning device 26 removes and cleans unnecessary substances such as toner remaining on the peripheral surface of the photosensitive drum 21. The charge removing device 27 removes charges from the cleaned circumferential surface of the photosensitive drum 21.

The sheet feeding device 3 is constituted by the following components and the like: a sheet storage 31 that stores a plurality of recording sheets 9 of a desired size, type, and the like for image formation in a stacked state; and a feeding device 33 that feeds out the recording sheets 9 stored in the sheet storage 31 one by one.

The paper storage bodies 31 are attached so as to be able to be pulled out of the casing 10, and a plurality of them are provided according to the mode of use. As the recording paper 9, for example, a recording medium such as plain paper, coated paper, thick paper, thin paper, or the like cut to a predetermined size can be used.

The fixing device 4 is configured by arranging fixing members such as a rotating heating member 41 and a rotating pressurizing member 42 formed in the form of a roller, a belt, and the like inside a casing 40 provided with an inlet and an outlet for recording paper 9.

The heating rotary member 41 and the pressurizing rotary member 42 are formed as a fixing processing portion: the recording sheets 9 are supported so as to rotate in contact with each other, and a desired fixing process (heating, pressing, etc.) is performed while the recording sheets 9, on which unfixed toner images are transferred, are sandwiched between the portions in contact with each other and the recording sheets 9 are passed through.

Then, the image forming apparatus 1 forms an image as follows. Here, a basic image forming operation when forming an image on one side of the recording paper 9 will be described as an example.

In the image forming apparatus 1, when a control unit (not shown) receives a command (signal) requesting an image forming operation from an external connection device, the image forming apparatus 2 rotates and starts the photosensitive drum 21 in the direction indicated by the arrow a, the charging device 22 charges the peripheral surface of the photosensitive drum 21 to a predetermined polarity and a predetermined potential (negative polarity in this example), and the exposure device 23 exposes the charged peripheral surface of the photosensitive drum 21 based on the input image information to form an electrostatic latent image having a desired pattern.

Next, in the image forming apparatus 2, the developing device 5 supplies toner charged to a desired polarity (negative polarity in this example) to the electrostatic latent image formed on the circumferential surface of the photosensitive drum 21, develops the electrostatic latent image, and develops the electrostatic latent image as a toner image. Thereby, a toner image is formed on the photosensitive drum 21.

Thereafter, in the image forming apparatus 2, the rotationally driven photosensitive drum 21 conveys the toner image to a transfer position opposed to the transfer device 25.

On the other hand, in the paper feeding device 3, the feeding device 33 feeds the recording paper 9 to the feeding and conveying path constituted by the conveying rollers 35 and 36, the paper guide member, and the like so as to match the timing at which the toner image formed by the image forming apparatus 2 reaches the transfer position, and finally, the recording paper 9 is fed by the conveying roller 36 and is supplied to the transfer position of the image forming apparatus 2.

At this time, in the image forming apparatus 2, at the transfer position, the transfer member of the transfer device 25 forms a transfer electric field between itself and the photosensitive drum 21, and electrostatically transfers the toner image on the photosensitive drum 21 to one surface of the recording paper 9. In the image forming apparatus 2, the cleaning device 26 continues to clean the peripheral surface of the photosensitive drum 21 during the image forming operation including the post-transfer period and the like, and the charge removing device 27 removes the charge from the peripheral surface of the photosensitive drum 21 after the cleaning. Thereby, the photosensitive drum 21 is held in a state ready for the next operation step of image formation.

Subsequently, the recording paper 9 to which the toner image is transferred is sent out from the transfer position and conveyed to the fixing device 4. In the fixing device 4, the recording paper 9 is introduced into a fixing processing portion between the rotary heating member 41 and the rotary pressurizing member 42 which are driven to rotate, and passes therethrough. When passing through the fixing processing portion, the toner of the toner image on one side of the recording paper 9 is heated and melted under pressure, and the toner image is fixed on the recording paper 9.

In the fixing device 4, the recording paper 9 on which fixing has been completed is sent out from the fixing processing section to a discharge conveyance path formed by a discharge roller 37, a paper guide member, and the like. Finally, the fixed recording paper 9 is discharged from the discharge port 12 of the casing 10 by the discharge roller 37 in the discharge conveyance path, and is stored in a discharge storage unit, not shown.

Through the above steps, a monochrome image composed of toner of one color is formed on one side of one sheet of recording paper 9, and the image forming operation on one side of the recording paper 9 is completed. When a command to execute a plurality of image forming operations is issued, the above-described series of operations is repeated similarly for the number of sheets.

Next, the developing device 5 will be explained.

As shown in fig. 2, 3, and the like, the developing device 5 includes a casing 50, and the casing 50 includes: a storage section 51 that stores the developer 8; conveying members 61 and 62 as an example of the rotating portion 60 that rotate to convey the developer 8 stored in the storage portion 51 in the longitudinal direction D; a developing roller 63 that holds the developer 8 conveyed by the conveying members 61, 62; a supply member 64 as an example of the rotation portion 60 that rotationally supplies the developer 8 from the storage portion 51 to the developing roller 63; and a layer thickness regulating member 65 that regulates the thickness of the layer of the developer held by the developing roller 63.

The housing 51 in the case 50 is provided with the following portions: two gutter- like passages 53, 54 that store the developer 8 and extend substantially parallel and long in one direction in which the conveying members 61, 62 respectively convey; and a developing portion 55 having a developing opening 55a, the developing opening 55a accommodating the developing roller 63 and exposing a part of the developing roller 63 to face a developing target portion of the photosensitive drum 21.

The adjacent portions of the two passages 53 and 54 are partitioned by the partition wall 56 along the longitudinal direction D, and are connected to each other at both ends of the longitudinal direction D by the connection portions 57A and 57B without the partition wall 56, thereby forming a passage through which the developer 8 can be circulated. As the developer 8, for example, a two-component developer containing a (non-magnetic) toner and a (magnetic) carrier is used.

The developing roller 63 is, for example, a roller including a cylindrical (non-magnetic) sleeve 63a rotating in the direction indicated by the arrow B and a magnet roller 63B disposed in a hollow portion of the sleeve 63 a. The shaft portion 63c of the developing roller 63 is rotatably supported by a bearing 633.

Further, the space S between the developing roller 63 and the photosensitive drum 21 is maintained at a fixed distance by providing a state in which a part of the space holding member 66 attached to the shaft portion 63c of the developing roller 63 is in contact with a portion supporting the photosensitive drum 21. Further, a developing bias is supplied from the power supply portion 635 to the shaft portion 63c of the developing roller 63, and a developing electric field is formed between the developing roller 63 and the photosensitive drum 21. As the developing bias, for example, a developing bias in which an ac component is superimposed on a dc component is supplied.

The supply member 64 is a member in the form of a rotating blade, a roller, or the like, and its shaft portion is rotatably supported by a bearing, not shown. The supply member 64 supplies a part of the developer 8 moving in the passage 54 toward the developing roller 63.

The conveying members 61 and 62 are members such as an auger having a spiral conveying blade formed on a shaft portion thereof, and the shaft portions are rotatably supported by bearings 613 and 623. The conveying members 61 and 62 rotate to convey the developer 8 while stirring it substantially in the axial direction.

The layer thickness regulating member 65 is a plate-like member disposed along the axial direction of the developing roller 63 with a predetermined gap from the developing roller 63. The layer thickness regulating member 65 regulates the layer thickness by scraping off an excess portion of the layer of the developer 8 held by the developing roller 63 into the housing portion 51.

As shown in fig. 3, in the housing 50, a portion 51A of the housing portion 51 that is positioned to overlap a region (developer holding region) E of the developing roller 63 that holds the developer 8 in the longitudinal direction D (hereinafter, also simply referred to as an "overlapping portion") is divided into a lower overlapping portion 51A1 and an upper overlapping portion 51A2 as shown in fig. 2, 4, 5, and the like.

As shown in fig. 2 and 5, the upper overlapping portion 51a2 at this time is a lid portion substantially corresponding to a lid that covers from above and closes a part of the passages 53 and 54 and the developing portion 55. On the other hand, as shown in fig. 2, 5, 6, and the like, the lower overlapping portion 51a1 becomes a main body portion corresponding to the main body of the passages 53, 54 and the developing section 55 except for the upper end portion occupied by the upper overlapping portion 51a 2.

As shown in fig. 3 and the like, case 50 includes left and right support portions 52A, 52B, and overlapping portions 51a1, 51a2 of left and right support portions 52A, 52B and housing portion 51 are joined to each other at both ends in longitudinal direction D.

The left and right support portions 52A and 52B mainly support the bearings 613 and 623 of the conveying members 61 and 62, the bearing 633 of the developing roller 63, and the shaft portion, not shown, of the supply member 64. Both support portions 52A and 52B are not divided in the vertical direction but are integrated, but may be divided into 2 parts in the vertical direction. However, by forming the components as an integral body, there is no need for an assembly operation of joining the components divided into 2 parts to integrate them when assembling the housing 50.

Further, support portions 52A, 52B are provided with end portions and connection portions 57A, 57B at portions on the side joined to receiving portion 51, end portions and connection portions 57A, 57B being portions of two passages 53, 54 other than the portions of passages 53, 54 in overlapping portions 51a1, 51a2 described above. Further, a replenishment path 58 is provided in a protruding state in one of the bearing portions 52A, and the replenishment path 58 is used for introducing and feeding the developer to be replenished into the passage 53. The conveying member 61 is provided with a replenishment conveying portion 61d in an extended state, and the replenishment conveying portion 61d is also present in the replenishment path 58 and has a replenishment blade that conveys the developer to be replenished to the passage 53.

In addition, the support portions 52A and 52B are provided with bearing attachment portions 52c (fig. 4) to which the bearings 613, 623, 633, and the like are attached, respectively, at portions on the opposite side to the side joined to the housing portion 51. A drive transmission portion 52d is provided in a portion of the one support portion 52B on the outer side of the bearing mounting portion 52c, and the drive transmission portion 52d is disposed and houses a gear train mechanism including the gear 634 of the shaft portion 63c of the developing roller 63, the gears 614 and 624 of the shaft portions of the conveying members 61 and 62, and the like.

As shown in fig. 2, the bearing units 52A and 52B are provided with two movable bearing units 71 and 72, and the two movable bearing units 71 and 72 support the developing device 5 so as to be movable in a direction away from the photosensitive drum 21 as indicated by an arrow C.

The movement support portions 71 and 72 are rod-like members extending in the longitudinal direction of the developing device 5 (the direction along the axial direction of the developing roller 63) at both upper and lower positions of the developing device 5. The upper movement support portion 71 is fixed by inserting the rod-like member through each of the through holes provided in the left and right support plates 70 attached to the outer surface portions of the support portions 52A, 52B in an upwardly protruding state. The lower movement support portion 72 is fixed by inserting the rod-like member through the respective through holes provided in the lower protruding portions 522 formed in the lower portions of the support portions 52A and 52B in a protruding state.

Further, the movement support portions 71 and 72 are provided with wheels, not shown, at both ends of the rod-like member so as to be rotatable, and the wheels are supported by support guide portions, not shown, which guide the wheels in the movement direction C and support the wheels. The support guide is provided in a part of the housing 10 or the like. Incidentally, the developing device 5 receives, for example, an urging force F (fig. 2) acting on a part of the support plate 70 in a direction approaching the photosensitive drum 21 from an unillustrated urging member.

Here, in the developing device 5, when a required period of time for performing an image forming operation or the like has elapsed, the conveying members 61 and 62, the developing roller 63, the supply member 64, and the like are rotated in predetermined directions by receiving rotational power from a driving device, not shown. Further, at this time, the developing roller 63 is supplied with a developing bias.

Thus, the developer 8 is conveyed in the paths 53 and 54 of the housing 51 of the casing 50 while being stirred in the direction indicated by the blank arrows substantially along the longitudinal direction D of the paths 53 and 54 by the conveying forces of the conveying members 61 and 62 rotating in the predetermined direction. At this time, the developer 8 moves to the passage 54 on the side closer to the developing roller 63 via the connecting portion 57B on the terminal end side of the passage 53 on the side away from the developing roller 63, and the developer 8 moves to the passage 53 via the connecting portion 57A on the terminal end side of the passage 54. As a result, the developer 8 is conveyed to circulate between the paths 53 and 54 in the storage section 51 as a whole.

Further, in the developing portion 55 of the casing 50, the supply member 64 supplies a part of the developer 8 conveyed in the passage 54 to the developing roller 63 and causes the developing roller 63 to hold the developer 8, the layer of the developer 8 held by the developing roller 63 is regulated to a desired layer thickness by passing through the layer thickness regulating member 65, and then the developing roller 63 conveys the developer 8 so that the developer 8 passes through the developing target portion opposed to the photosensitive drum 21.

When the developer 8 held by the developing roller 63 passes through the developing object portion, the developer 8 is transferred and attached to the electrostatic latent image of the photosensitive drum 21 by the developing electric field formed between the developing roller 63 and the photosensitive drum 21 by the developing bias. Thereby, the electrostatic latent image is developed.

In the developing device 5, as shown in fig. 3 to 6, etc., the lower overlapping portion 51A1 of the portion 51A of the housing portion 51 overlapping the developer holding area E of the developing roller 63 is formed of metal throughout the overlapping area.

As the metal, for example, aluminum is used from the viewpoint of being easily produced by extrusion molding, but not limited thereto.

As shown in fig. 7 (a), the cross-sectional shape of the metal-molded lower overlapping portion 51a1 in the direction orthogonal to the longitudinal direction D is configured to be the same shape over the entire region in the longitudinal direction D.

The lower overlapping portion 51a1 having such a cross-sectional shape can be produced by, for example, metal extrusion molding or drawing molding. In the case where the cross-sectional shape of the lower overlapping portion 51a1 is not formed in the same shape over the entire region in the longitudinal direction D, the production of the lower overlapping portion 51a1 using metal may be performed by a molding method such as cutting.

In the developing device 5, the upper overlapping portion 51A2 of the overlapping portion 51A and the supporting portions 52A and 52B are molded from an electrically insulating material. The upper overlapping portion 51a2 of the housing portion 51 of the developing device 5 is also molded from an electrically insulating material.

As the material having electrical insulation, for example, ABS resin, liquid crystal polymer, glass-containing resin, or the like is used. The electrical insulation property at this time is a property to the extent that at least the electricity of the developing bias supplied to the shaft portion 63c of the developing roller 63 can pass. In the case of using synthetic resin as a material having electrical insulation, upper overlapping portion 51a2 and support portions 52A and 52B are produced by a plastic molding method.

In the developing device 5, the following configuration is adopted in order to couple the lower overlapping portion 51a1 formed of metal to the support portions 52A and 52B formed of a material having electrical insulation.

That is, as shown in fig. 8, on surface 52j of support portions 52A and 52B joined to lower overlapping portion 51a1, a plurality of projections 75 are provided which contact joint surface 51j of lower overlapping portion 51a 1. The projection 75 is formed in a disc (or a column) shape having a desired projection amount h (see fig. 9), for example. The projections 75 are provided in the required number at the desired positions.

Further, a through hole 77 is provided in a substantially central portion of the convex portion 75, and the screw 76 for coupling with the lower overlapping portion 51a1 passes through the through hole 77. In this case, the projection 75 may be said to be a portion provided around the screw through hole 77 (and also the screw 76). On the other hand, as shown in fig. 7B, a screw hole (female thread) 59 for fastening the screw 76 is provided on the joint surface 51j of the lower overlapping portion 51a 1. The screw holes 59 are formed at positions corresponding to the through holes 77, and are formed in a number corresponding to the through holes 77.

As shown in fig. 7 (B), a plurality of positioning projections 512 are provided on the joining surface 51j of the lower overlapping portion 51a1, and the positioning projections 512 are used to determine the positions at the time of joining with the support portions 52A and 52B. On the other hand, as shown in fig. 8, a plurality of positioning holes 78 into which a plurality of positioning projections 512 are fitted are provided on the joint surface 52j of the support portions 52A, 52B. The positioning projection 512 is provided by, for example, providing a mounting hole (recess) in the metal joint surface 51j and then press-fitting a member to be a projection.

Further, as conceptually shown in fig. 9, elastic member 81 is attached to at least a part of surface 52j of support portions 52A, 52B that is joined to lower overlapping portion 51a 1.

The elastic member 81 is mainly used to prevent the leakage of the developer 8 after the bearing portions 52A, 52B are coupled with the lower overlapping portion 51a1, and is minimally installed at a portion where the leakage is required to be prevented. As the elastic member 81, any material may be used as long as it is deformed by itself when the support portions 52A, 52B are joined to the lower overlapping portion 51a1, and for example, a member such as urethane sponge (or rubber) may be used. The elastic member 81 is attached to the corresponding portion of the attachment surface of the support portion 52A, 52B by an adhesive means such as an adhesive or a double-sided tape.

Further, as shown in fig. 9, as elastic member 81, a member having a thickness d (> h) exceeding the protruding amount h of convex portion 75 before the coupling of support portions 52A, 52B and lower overlapping portion 51a1 is mounted. The thickness d may be appropriately selected from the viewpoints of physical properties, airtightness, and the like of the elastic member 81. As shown by the blank portion in fig. 9, the elastic member 81 is not attached to the portion covering the projecting surface 75a of the projection 75. Although the elastic member 81 may be attached to a portion covering the protruding surface 75a of the convex portion 75, when the elastic member is not attached to this portion, the convex portion 75 can be reliably brought into contact with the engaging surface 51j of the overlapping portion 51a1 of the lower portion, and the position at the time of coupling can be aligned.

As shown in fig. 9 (a), the coupling between lower overlapping portion 51a1 and support portions 52A and 52B is performed as follows: the engaging surfaces 51j and 52j are brought close to each other, and the screw 76 is fastened to the screw hole 59 after passing through the through hole 77 of the boss 75.

During the fastening of the screw, positioning projection 512 is fitted into positioning hole 78, and support portions 52A and 52B and lower overlapping portion 51a1 are positioned, and as shown in fig. 9 (B), convex portion 75 is in contact with joint surface 51j of lower overlapping portion 51a1, and support portions 52A and 52B are joined to lower overlapping portion 51a 1.

As shown in fig. 9 (B), when the screw is tightened for coupling, the elastic member 81 comes into contact with the joint surface 51j of the lower overlapping portion 51a1 and is then compressed by elastic deformation to be in close contact with the joint surface 51 j. As a result, the elastic member 81 is compressed, so that the thickness thereof at the time of completion of the coupling is the same as the projection amount h of the convex portion 75.

Further, in developing device 5, upper overlapping portion 51A2 of overlapping portion 51A of housing 51 is engaged with lower overlapping portion 51A1 and support portions 52A, 52B by screws or the like. In the coupling at this time, the projection 75 having the screw through hole 77, the positioning projection 512, and the positioning hole 78 may be similarly used.

As described above, in the developing device 5 of embodiment 1, since the overlapping portion 51A1 at the lower portion of the overlapping portion 51A of the housing portion 51 of the casing 50 is formed of metal, the rigidity can be improved as compared with the case where the housing portion 51 of the casing 50 is not formed of metal.

Accordingly, for example, even when the developing device 5 is configured to be large in size as a whole or is configured to be long in the longitudinal direction D, sufficient rigidity (strength) can be secured against a load applied to store or hold the developer 8, the conveying members 61 and 62, and the like, and there is no fear of warping or bending occurring in the overlapping portion 51A of the storage portion 51 in the housing 50.

In the developing device 5, since the supporting portions 52A and 52B are molded from a material having electrical insulation properties, for example, even when a developing bias is supplied to the shaft portion 63c of the developing roller 63 during an image forming operation, electrical insulation properties of the supporting portions 52A and 52B supporting the shaft portion 63c of the developing roller 63 can be ensured, and therefore, there is no fear that electricity flows through the overlapping portion 51a1 of the lower portion molded from metal in the housing portion 51.

In developing device 5, since lower overlapping portion 51a1 formed of metal is bonded to support portions 52A and 52B formed of a material having electrical insulation with projection 75 interposed therebetween, both of lower overlapping portion 51a1 and support portions 52A and 52B are easily positioned with projection 75 interposed therebetween and are well bonded thereto, as compared with the case where bonding is performed without projection 75 interposed therebetween (bonding of large surfaces to each other).

In the developing device 5, since the projection 75 is provided in the portion surrounding the through hole 77 of the screw 76 or the portion surrounding the screw 76 at the time of fastening, the overlapping portion 51a1 of the lower portion of the housing portion 51 formed of metal and the support portions 52A and 52B can be more reliably positioned and firmly coupled to each other than the case where the projection 75 is not provided in the portion surrounding the through hole 77 or the portion surrounding the screw 76 at the time of fastening (for example, the case where the projection 75 is provided in a portion different from the portion where the screw 76 is fastened).

In developing device 5, since the elastic member having thickness d exceeding projection amount h of convex portion 75 is interposed and bonded before bonding lower overlapping portion 51a1 and support portions 52A and 52B, a gap is suppressed from being generated in a surface of receiving portion 51 where lower overlapping portion 51a1 formed of metal is bonded to support portions 52A and 52B with elastic member 81 interposed therebetween, compared to the case where elastic member 81 having thickness d not exceeding projection amount h of convex portion 75 is interposed and bonded before bonding. Thus, in developing device 5, there is little concern that developer 8 may leak from the portion where lower overlapping portion 51a1 and support portions 52A and 52B are joined together with elastic member 81 interposed therebetween.

Other embodiments are also provided.

In embodiment 1, the description has been given of the case where only the lower overlapping portion 51a1 of the housing portion 51 of the housing 50 of the developing device 5 is formed of metal, but the upper overlapping portion 51a2 of the housing portion 51 may also be formed of metal.

In this case, the rigidity of the developing device 5 is further improved as compared with the case where only the lower overlapped portion 51a1 is formed of metal.

In addition, although the case where the overlap portion 51a1 of the lower portion formed of metal is produced at one time by the extrusion molding method or the like has been described in the above embodiment 1, the overlap portion 51a1 of the lower portion formed of metal or the like may be configured by joining a plurality of divided portions divided with a surface (divided surface) 51D along the longitudinal direction D as a boundary, as shown in fig. 6, for example. The lower overlapping portion 51A1 illustrated in fig. 6 is formed of two divided portions, i.e., A1 st lower overlapping portion 51A1a and a2 nd lower overlapping portion 51A1b, with a plane 51D extending in the longitudinal direction D as a boundary.

In this case, the lower overlapping portion 51a1 formed of metal can be more accurately produced than a case where the lower overlapping portion 51a1 formed of metal of the housing portion 51 is not divided into a plurality of portions.

Although embodiment 1 has been described above with respect to the case where convex portion 75 is provided on joint surface 52j of support portions 52A and 52B, convex portion 75 may be provided on joint surface 51j of lower overlapping portion 51A formed of metal. The convex portion 75 is not limited to a portion provided around the screw 76 (or the through hole 77 thereof) at the time of fastening, and may be provided at other portions or provided at other portions corresponding to the surrounding portion.

In embodiment 1, the left and right support portions 52A and 52B may be configured as, for example, left and right 1 st support portions for supporting the bearings 633 of the developing roller 63, left and right 2 nd support portions for supporting the bearings 613 and 623 of the conveying members 61 and 62, and the shaft portion of the supply member 64, which is not shown.

In this case, if the 1 st supporting portion and the 2 nd supporting portion are formed of the same material (for example, a material having electrical insulation), the supporting portion that also supports the shaft portion of the rotating portion such as the conveying members 61 and 62 and the supply member 64 can be formed integrally with the bearing 633 of the developing roller 63. Further, when the developing roller is molded using a material having electrical insulation, the bearing 633 of the molded developing roller 63 can be integrally molded with a support portion that also supports the shaft portion of the rotating portion such as the conveying members 61 and 62 and the supply member 64, and electrical insulation can be ensured.

In embodiment 1, although the image forming apparatus 1 including the developing device 5 described above is exemplified as an apparatus for forming a monochrome image, an image forming apparatus having another form or the like (for example, an apparatus for forming a multicolor image) can be employed as long as the developing device 5 of the present invention can be applied.

In the case of an image forming apparatus that forms a multicolor image, a plurality of developing devices necessary for color reproduction of the multicolor image are applied as the developing devices 5. In this case, the transfer method of the image forming apparatus 2 is not limited to the direct transfer method, and may be an intermediate transfer method (intermediate transfer apparatus).

The developing device 5 to which the present invention is applied may be a developing device of another form as long as it includes the casing 50 having the developing roller 63 and the housing 51.

Claims (11)

1. A developing device, wherein,

the developing device includes a housing having: a housing section that houses a developer; a rotating part which rotates to convey the developer stored in the storing part along the length direction; and a developing roller holding the developer conveyed by the rotary portion,

at least a part of the housing portion is formed of metal over a region overlapping with a developer holding region of the developing roller in the longitudinal direction.

2. The developing device according to claim 1,

the supporting portion of the housing, which is engaged with the accommodating portion and supports the shaft portion of the developing roller, is molded from an electrically insulating material.

3. The developing device according to claim 2, wherein,

the 2 nd support portion of the housing, which supports the shaft portion of the rotating portion, is molded from an electrically insulating material and is integrated with the support portion that supports the shaft portion of the developing roller.

4. The developing device according to claim 1,

the metal molded portion of the housing portion has a cross section in a direction orthogonal to the longitudinal direction, the cross section having the same shape.

5. The developing device according to claim 2 or 3,

a convex portion that comes into contact with the other joining surface is provided on the joining surface of at least one of the support portion and the 2 nd support portion of the housing portion, and the portion of the housing portion that is formed of metal is coupled to the support portion or the 2 nd support portion by a screw in a state where the convex portion comes into contact with the other joining surface.

6. The developing device according to claim 5,

the convex portion is provided on a surface of the support portion to be joined or a surface of the 2 nd support portion to be joined.

7. The developing device according to claim 5 or 6,

the projection is provided at least in a portion surrounding the screw.

8. The developing device according to any one of claims 5 to 7,

the portion of the housing portion formed of metal is joined to the support portion and the 2 nd support portion with an elastic member interposed therebetween at least in part of surfaces joined to each other,

the elastic member has a thickness exceeding a protruding amount of the convex portion before the coupling.

9. The developing device according to claim 8,

the elastic member is attached to the joint surface of the support portion and the joint surface of the 2 nd support portion.

10. The developing device according to claim 4,

the portion of the housing portion formed of the metal is formed by joining a plurality of divided portions obtained by dividing a surface along the longitudinal direction as a boundary.

11. An image forming apparatus in which, when a toner image is formed,

the image forming apparatus includes the developing device according to any one of claims 1 to 10.

Images